FIG. 1 shows a structural schematic diagram of a vibrating ring gyroscope according to the prior art. As shown in the figure, the vibrating ring gyroscope according to the prior art comprises a driving structure, which includes a ring 10, which is a conductor, a plurality of sensing electrodes 20 set above or below the ring 10, and a plurality of driving electrodes 30 set on the outer side of the ring 10 and corresponding to the sensing electrodes 20. The ring 10 and the driving electrodes are connected to a voltage source, respectively, and thereby have a voltage difference therebetween. Accordingly, when the ring 10 and the driving electrodes 30 are electrified, they will attract each other, and hence the ring 10 will be stretched and deformed.
FIG. 1B shows a motion schematic diagram of FIG. 1A. As shown in the figure, when the ring 10 and A- and C-driving electrodes 30 are electrified, because the ring 10 and the driving electrodes 30 attract each other, the ring 10 will stretch towards the directions of the points A and C. Thereby, the points B and D will move towards the center of the ring 10. If the vibrating ring gyroscope rotates about the axis formed by the line connecting the points A and C, each point on the ring 10 will experience a Coriolis force FC, which is equal to m·V×Ω, namely, 2 mVΩ Sin θ, where m is the mass of the point under force, V is the velocity of the point under force, Ω is the directional vector of rotation of the point under force, and θ is the angle between the vectors V and Ω. Because the vibrating ring gyroscope rotates about the axis formed by the line connecting the points A and C, the direction of the vector Ω is the direction of the line connecting the points A and C, namely, the direction of X-axis.
FIG. 1C shows a driving-mode curve of a vibrating ring gyroscope according to the prior art. When the ring 10 and the A- and C-driving electrodes 30 are electrified, the velocity of the point A is V, the velocity of the point B is −V, the velocity of the point C is −V, and the velocity of the point D is V. Thereby, the curve shows a Cos 2ψ pattern. Accordingly, the driving mode of the vibrating ring gyroscope is Cos 2ψ.
FIG. 1D shows a sensing-mode curve of a vibrating ring gyroscope according to the prior art. According to the above description, it is known that the points A and C are free from the Coriolis force because the θ angle between the velocity and angular velocity is zero. On the other hand, the points B and D will experience a downward and an upward Coriolis force, respectively. The amplitude of the force FC experienced by the points on the ring 10 is shown as the curve in FIG. 1D. In FIG. 1D, a Sin ψ curve is shown. Thereby, when the ring 10 and the A- and C-driving electrodes 30 are electrified, the sensing mode of the vibrating ring gyroscope is Sin ψ.
Likewise, if the ring 10 and the B- and D-driving electrodes 30 are electrified, the vibrating ring gyroscope rotates about the axis formed by the line connecting the points B and D. Thereby, the directional vector of Ω is the direction of the line connecting the points B and D. In addition, the sensing mode of the vibrating ring gyroscope is Cos ψ. Accordingly, the vibrating ring gyroscope according to the prior art adopts out-of-plane Cos ψ and Sin ψ resonance mode to measure the angular velocity of X-Y-axes. However, because the sensed signals are limited by the area of the bulk of the resonance ring of the gyroscope, the intensity of the sensed signals cannot be increased effectively.
FIGS. 2A and 2B show a structural and a motion schematic diagram of a vibrating ring gyroscope according to the U.S. Pat. No. 6,343,509, which adopts out-of-plane Cos 3ψ and Sin 3ψ resonance mode to measure the angular velocity of X-Y-axes. However, because the amplitude of the 3ψ-mode is smaller than that of ψ- and 2ψ-mode, the intensity of the sensed signals cannot be increased effectively.
Accordingly, the present invention provides a sensing structure for a multiaxial gyroscope, which can increase effectively the sensing area as well as the sensing mass of the gyroscope, so that the driving amplitude is increased accordingly. Thereby, the intensity of the sending signal can be increased effectively. In addition, the Cos ψ and Sin ψresonance mode adopted by the present invention can increase the driving amplitude. Hence, the problems described above can be solved.